This invention relates to internal combustion engines, and more particularly concerns an improved four cycle, poppet valve type piston driven internal combustion engine.
Four cycle piston driven internal combustion engines are generally characterized by having at least one piston which reciprocates within a combustion cylinder and drives a crankshaft in a rotary manner. As the piston moves through one downward stroke and one upward stroke, the engine's crankshaft turns one revolution. An additional downward and upward stroke of the piston completes another revolution of the crankshaft. The piston's four strokes are typically referred to as intake, compression, power, and exhaust. Such engines utilize poppet type intake and exhaust valves which allow a combustable gas mixture to enter the cylinder, and enable burned gases to escape. The poppet valves are held in a normally closed position by a coil spring, and are momentarily forced to opened positions to coincide with the aforesaid strokes or stages of the piston. The opening of the valves is generally achieved by a camshaft having a series of elliptical lobes which, when rotated, push the valves against the urging of the spring. The camshaft is generally coupled to the crankshaft through mechanical systems known as valvetrains which may comprise gears, belts and/or chains, said valvetrains serving to turn the camshaft synchronously with the crankshaft. The camshaft is commonly turned at half the speed of the crankshaft in order that each valve will open once during the four cycles.
Four cycle engines usually do not efficiently transfer torque from the piston to the crankshaft because each power stroke must turn the crankshaft through two complete revolutions and turn the camshaft through one complete revolution. Frictional and inertial forces adversely affect the engine's torque output. Additionally, the moving parts necessary to drive the valvetrain are susceptible to premature wear and replacement. Furthermore, the timing components and camshaft are expensive to manufacture and contribute significantly to the cost of the engine.
Various mechanical movements have earlier been disclosed which convert reciprocal motion to rotational movement. One such mechanical movement is known as the trammel crank gear. The unique feature of the trammel crank gear is that one revolution is produced for four strokes of a reciprocating member.
The trammel crank gear is comprised of:
(a) an elongated action arm having distal and proximal extremities, said distal extremity confined to linear reciprocal movement.
(b) a first sliding block pivotably attached to said proximal extremity, and a second sliding block pivotably attached to the same side of said arm and closer to said distal extremity, said blocks being of identical configuration and adapted to rotate in the same plane parallel to the axis of said arm,
(c) a rotating disc having a front surface facing said arm, and an opposed rear surface, said disc having two straight channels recessed from said front surface, traversing the diameter of the disc, and intersecting at right angles at the center of said disc, said channels adapted to accept said sliding blocks and constraining said blocks to reciprocal linear motion as said disc rotates, and
(d) an axle perpendicularly emergent from the center of the rear surface of said disc.
It is accordingly an object of this invention to provide a piston driven four cycle internal combustion engine which efficiently transfers torque output from the pistons to the crankshaft.
It is another object of the present invention to provide a piston driven four cycle internal combustion engine having fewer moving parts than conventional engines of this type.
It is a further object of the present invention to provide a piston driven internal combustion engine which is less expensive to manufacture than conventional engines of this type.
These objects and other objects and advantages of the invention will be apparent from the following description.